Remote monitoring of cargo shipping reefer containers is a relatively new technical field. In connection with remote monitoring, cargo shipping reefer containers are configured with a refrigeration system that has installed therewith a control computer coupled with sensors monitoring the operation of the refrigeration system. Cargo shipping reefer containers typically conform to the ISO standard and are also denoted reefer ISO-containers.
An ISO-container is an article of standardized transport equipment which is very widely used in commercial transport. Typically, ISO-containers have lengths of 20, 40 or 45 feet and have standard fittings that can be used for attachment to vehicles and for stacking on-board carriers. Most ISO-containers have a unique combination of letters/numbers that enable unique identification thereof.
Many of the containers are reefer containers that are provided with a refrigeration system or an environment regulating system configured for keeping the cargo at a set temperature and/or humidity—often within quite narrow tolerances. For instance, a 40 ft container is usually constructed with a 38 ft cargo space and a 2 ft refrigeration apparatus.
Today, more than about 90% of international cargo is transported in containers. The containers carry cargo literally all over the world, from the southernmost regions to the northernmost regions and vice versa. A large part of that cargo is in the form of foodstuffs that are transported for many days from one part of the world to another. The qualities of the foodstuffs that arrive at their destination following transport in containers depend to a very high degree on the efficiency and performance of the refrigeration or environment regulating system. If a refrigeration system or an environment regulation system breaks down during transport of the cargo, the cargo will usually be ruined when it arrives at its destination.
Conventionally, the cargo business has accepted this state of affairs due to it being impossible, from a technical point of view, to provide reliable monitoring systems that function in the very diverse situations to which a refrigeration container and the refrigeration and environment regulating systems are exposed. For instance, the container may be subject to widely varying ambient temperatures and widely differing humidity levels. The temperature of the cargo as such may vary a lot, and so may the nature of the cargo.